1. Field of the Invention
The present invention relates to a method of controlling multiple/single mode in a wideband wireless local loop (W-WLL) network system. More particularly, the present invention relates to a radio interface unit (RIU) and a method of controlling multiple/single mode of such an RIU in a wireless local loop (WLL) system, in which both the multiple and single mode services can be performed by a single algorithm, and a modulator-demodulator (modem) used in RIU is modeled as xe2x80x9cmasterxe2x80x9d and xe2x80x9cslavexe2x80x9d, respectively, to thereby allow a rapid handling of service, a stabilized system, and an efficient utilization of wireless systems.
2. Description of the Related Art
In general, WLL system is similar to a mobile communication network in that WLL system uses wireless channels as a communication medium. However, WLL system is not provided with mobility, and therefore, a communication environment thereof is further excellent than that of mobile communication system.
WLL system has further advantage in that a line-of-sight environment is secured and a propagation path loss is low, say, is approximately 20 dB/decade, thus allowing a wide area service using the same amount of transmitting power. In addition, WLL system is a fixed communication system employing a point-to-point transmission method, and has less fading caused by a multiple path than the propagation environment of mobile communication system that employs a point-to-station transmission method.
Due to such advantages, development and study on WLL system has been actively performed. FIG. 1 is a schematic view of a common WLL network system having the above-described advantages.
The WLL network system shown in FIG. 1 consists of a terminal 10, a radio interface unit(RIU) 20, a radio port (RP) 30, a radio port controller 40, a WLL exchanger 50, and a radio port operation and maintenance center (RPOM) 60.
An inter-working function (IWF) 70, and a home location resister/authentication center are added to thus-configured WLL system.
WLL system further includes a network management center 90 connected to RPOM 60 and WLL exchanger 50, and a charging center 100 connected to WLL exchanger 50 and IWF 70.
Thus-configured WLL has an interface method among network components as follows.
A common WLL interface standard is used as an interface standard between RIU 20 and RP 30, wherein a channel bandwidth is 10 MHz. Either E1 wire connection or HDSL is used as an interface standard between RP 30 and RP controller 40, and link access procedure D(LAPD) as a signal transmission protocol. E1 wire connection is used as an interface standard between RP controller 40 and WLL exchanger 50, and ITU.T G.965 as a signal transmission method. Ethernet is used between RP controller 40 and RPOM 60 as an interface standard, and simple network management protocol (SNMP), filter transfer protocol (FTP), telecommunication network (TELNET) and the like as a signal transmission method. E1 wire connection is employed between RP controller 40 and IWF 70 as an interface standard, and LAPD as a signal transmission protocol. In addition, E1 wire connection is employed as an interface standard between WLL exchanger 50 and IWF 70, and R2 as a signal transmission method. E1 wire connection is employed as an interface standard between WLL exchanger 50 and home location register (HLR), and IS-41C as a signal transmission method.
A conventional WLL system has the above-described components operating as follows.
First, RP 30 is made up of a radio port control module for performing an overall management function onto the radio port, a modem module for performing CDMA channel-related signal processing function, an RF module for performing a high power/low noise amplification and a transmitting/receiving frequency converting function, and a line connection module for linking to E1 wire connection for a match with RP controller 40.
Thus-structured RP 30 performs such functions as a transmitted signal amplification, low noise amplification of a received signal, frequency upward/downward conversion, diversity receipt via two antennas, high power/low noise amplification, and transmitting/receiving frequency conversion. In addition, modem module performs provider function of CDMA channel(pilot channel, synchronization channel, paging channel, access channel, signaling channel, traffic channel, packet traffic channel and packet access channel), digital baseband function, and CDMA channel coding and decoding-related function. In addition, line connection module performs data communication with the RP controller in regards of traffic and control data, and link line (E1/HDSL) function for a match with RP controller.
RP controller 40 for controlling RP 30 includes a transcoder module, a call processing module, a switching module, and a matching module.
The transcoder module further includes a transcoder for converting to 64 kbps PCM voice coded signal, and is provided with an echo canceller function. The call processing module is a processor for performing various kinds of call processing functions, for example, supporting of transmitted/received call processing of radio port, and processing of messages, and other functions like management of subsystem within RP controller and formatting of control signal between WLL exchanger and subscriber interface equipment. The call processing module has a duplex structure for system reliability enhancement.
The switching module provides a traffic path between an RP matching equipment and a transcoder in RP. The matching module consists of an WLL exchanger matching module, an RP matching module, and an RPOM matching module, wherein WLL exchanger matching module performs E1/G.965 digital link matching function when the RP controller is installed in remote location with respect to the WLL exchanger. The RP matching module serves as a match of E1/LAPD, HDSL link line between RP and RP controller, and RPOM matching module serves as a match of Ethernet/SNMP, FPT, TELNET between RPOM and RP controller.
RPOM 60 operates RPC 40, RP 30, and RIU 20, and serves to the maintenance of the above-described equipment.
RIU 20 includes a high frequency processing module 21, a modem 22 for processing a digital signal, and a subscriber interface module 23, as shown in FIG. 2.
Here, high frequency processing module 21 amplifies a transmitted signal, low noise of a received signal, and performs a frequency upward/downward converting function. That is, high frequency processing module 21 transmits/receives data to/from a radio port via an antenna. Subscriber interface module 23 consists of BRI, SLIC, and SIO, etc, wherein BRI provides ISDN U-interface function for a physical interface with ISDN subscribers. SLIC performs A/D conversion and D/A conversion by being linked to an analog line, and serves as a line feeder, and ring signal and tone signal provider. SIO interfaces with RS-232C for a connection with a serial port so as to provide a digital data terminal interface function.
Modem 22, a digital processing block, is connected to high frequency processing module 21 in a searcher 22a so as to extract only a desired channel signal from the received signal. A power controller 22b controls power by detecting the strength of the channel signal extracted by searcher 22a. In addition, a phase tracking portion 22c traces a phase from a channel signal extracted by searcher 22a, and performs an automatic frequency control function, when phase difference occurs, so as to compensate such a phase difference. An automatic gain controller 22d variably controls the gain of the amplifier in accordance with the strength of the received signal obtained from searcher 22a. A receiver 22e serves to convert CDMA signal of RF band passed through searcher 22a to a baseband signal. Thus-converted baseband signal undergoes a series of process, say, demodulation, de-interleaving, and channel decoding in a channel encoder/decoder 22f, and is transmitted to subscriber interface module 23. In addition, subscriber data transmitted from subscriber interface module 23 is modulated to CDMA signal, interleaved, and channel coded in channel encoder/decoder 22f, and is band-diffused in a bad diffuser 22g. The band-diffused signal is filtered to a predetermined band in FIR filter 22h, transmitted to high frequency processing module 21, and is transmitted as an RF signal.
However, such a subscriber interface equipment is in a single mode (one traffic channel and one signal channel) where only a single modem is used. If a subscriber interface equipment is configured in a multiple mode (plural traffic channels and a single signal channel) employing a plurality of modems, an activated modem among a plurality of modems has to perform an automatic frequency control (AFC) function, power control (PC) function, and automatic gain control (AGC) function, thus causing frequent switching of the modem. That is, when a first modem performs an interface, the first modem also has to perform such functions as an automatic frequency control, automatic gain control, and power control, and when a second modem also has to perform an interface, the second modem also has to perform functions same as those of first modem, a modem switch is required.
Accordingly, since the multiple mode subscriber equipment is implemented using a plurality of modems, a frequent modem switching is required. In such a case, a speedy modem switching is required, which disturbs smooth operation of each modem in such functions as an automatic frequency control, automatic gain control, and power control.
Therefore, it is an object of the present invention to provide a multiple/single mode control method in wireless local loop network system which allows both multiple and single mode services by a single algorithm.
It is another object of the present invention to provide a radio interface unit in wireless local loop network system which allows stability of system and an efficient use of wireless source by implementing a modem of the radio interface unit in the concept of master and slave so as to achieve a speedy service handling.
To accomplish the above object of the present invention, there is provided a radio interface unit in wireless local loop network system, in which the radio interface unit includes a subscriber interface module for interface with subscriber terminal and data, a high frequency processing module for transmitting/receiving radio data to/ from the radio port via an antenna, and a modem for converting and interfacing data between the subscriber interface module and the high frequency module, the radio interface unit including: a modem unit having a master modem which performs an automatic frequency control function for a direct control of a high frequency, power control function, and automatic gain control function, and is provided with a pilot channel, power control channel, and signaling channel only when the master modem operates as a primary one, and a plurality of slave modems which have the pilot, power control, and signaling channels and receive the power control and signaling channels only when the slave modems operate as a primary modem, and which receive only the power control channel and signaling channel when they operate as a secondary modem; and a control module for controlling transmitting/receiving state of the modem unit and state of the subscriber interface module.
To accomplish the above object of the present invention, there is provided a method of controlling a single mode of radio interface unit in wireless local loop network system, in a method of controlling radio interface unit in wireless local loop network system, the method of controlling a single mode of radio interface unit including: a first step of obtaining a pilot signal by initializing master/slave modems and shifting the master modem into a state where a pilot signal is obtained; a second step of obtaining a synchronization by shifting the master modem to a state where a synchronization is obtained; a third step of receiving system information message, shifting the modem to a call processing standby state, and confirming whether a call request exists or not; a fourth step of achieving power control and call processing by confirming whether the call request is an initial event or not, when the call request exists, and setting the master modem to a primary modem if the call request is an initial event; a fifth step of setting the slave modem to a secondary modem when the call request is not an initial event, performing power control on the secondary modem via the master modem, and controlling the secondary modem to perform the call processing; a sixth step of releasing the call connected via the master modem and shifting the master modem to a call standby state when the call processing in the master modem ends in the fifth step, and checking the state of the secondary modem and performing power control on the master modem when the secondary modem is in a call state; and a seventh step of releasing the call which is connected to the secondary modem when the call processing in the secondary modem ends, shifting the secondary modem to a call standby state, and completing the control on modems.
To accomplish the above object of the present invention, there is provided a method of controlling a multiple mode of radio interface unit in wireless local loop network system, in a method of controlling radio interface unit in wireless local loop network system, the method of controlling a multiple mode of radio interface unit including: a first step of obtaining a pilot signal by initializing master/slave modems and shifting the master modem into a state where a pilot signal is obtained; a second step of obtaining a synchronization by shifting the master modem to a state where a synchronization is obtained; a third step of receiving system information message, shifting the master and slave modems to a paging state, and confirming whether a call request exists or not; a fourth step of achieving power control and call processing by activating the master modem to an access mode when a call request is occurred via the master modem, allocating a channel thereto, and setting the master modem to a primary modem; a fifth step of setting the slave modem to a secondary modem when a call request occurs via the slave modem during call processing of the master modem, and controlling the secondary modem to perform the call processing; a sixth step of activating the slave modem to an access mode when a call request is occurred via the slave modem, allocating a channel thereto, setting the slave modem to a primary modem, performing a power control on the slave modem via the master modem, and controlling the slave modem to perform the call processing; a seventh step of setting the master modem to a secondary modem when a call request occurs via the master modem during a call processing of the slave modem, and controlling the secondary modem to perform a call processing; an eighth step of releasing the call connected to the master modem if the call processed in the master modem ends at the state where the master modem operates as a primary modem and the slave modem operates as a secondary modem, and setting the slave modem to a primary modem; and a ninth step of releasing the call connected to the slave modem if the call processed in the slave modem ends at the state where the slave modem operates as a primary modem and the master modem operates as a secondary modem, and setting the master modem to a primary modem.